Yielding propeller



Jul 14, 1931. E. A. MARSH YIELDING PROPELLER Filed March l1 1929 atented July 14, 1931 UNITED STATES PATENT OFFICE ESLI A. MARSH, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T REGIS PAPER COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW 'YORK I upon the upper end of the bearing.

YIELDING- PROPELLER I Application filed March 11, 1929. Serial No. 345,927.

This invention relates to a yielding propeller and more particularly to such a propeller adapted to propel granular, pulverulent, or similar compressible material. The purpose of the invention is to provide a propeller which will pack granular or pulverulent material to a predetermined degree and exert on the material a pressure up to the desired degree and will then yield so as not to increase the pressure to any con siderable extent above the usual amount even if the material no longer-moves away from the propeller. Minor objects and details of the invention will appear as the. description proceeds.

In the accompanying drawings forming part of this specification, Figure 1 is a vertical section through apparatus embodying my invention; Fig. 2 is a cross section substantially on the line 22 of Fig. 1; Fig. 3 is a plan view of a roller bearing.

The invention is shown employed in a de vice for conveying materials, and in com bination with a centrifugal propeller. In the construction of the apparatus illustrated, there is a hopper 10 having at its bottom end a casing 11 somewhat larger than the hopper and containing a rotor 12 driven by a shaft 13, the rotor being adapted to drive material out of a delivery spout 1 1.

It is desired to press the material down upon the rotor with a certain amount of force in order that the rotor may act upon the compacted material. The means em ployed for this comprises two blades 15 and 16 each of which is provided with a stem 17 passing through a hole in a sleeve 18. The inner end of each stem 17 within the hollow sleeve is turned at right angles as indicated in dotted lines in Fig. 2 to form a crank 19. Preferably, the end is raised slightly above the plane of the attached blade.

The upper end of sleeve 18 is mounted in a bearing 20 and carries a gear 21 resting Gear 21 meshes with gear 22 which may be driven in any suitable manner and so impart rotary motion to the sleeve.

Inside of the sleeve there is a shaft 23 the lower end of which rests upon cranks 19. The upper end of the shaft carries a pivoted member 2 1 provided with a ball bearing on which there rests a lever 25 fulcrumed to the frame at 26 and provided with an adjustable weight 27.

When the blades are turned in the direction of arrow 28, the blades are driven so as to crowd material 29 in the hopper down into the casing of the centrifugal impeller. By this movement the material is compacted to a certain extent below line 30, as is indicated in the drawings. The parts 'arepreferably proportioned so that normally the centrifugal propeller advances the material as fast as it is compacted by the blades of the screw propeller, but it may be desirable under some circumstances to continue the rotation of the screw propeller while stopping the centrifugal propeller or it may be desired to continue the rotation of both while stopping the flow of the material from outlet 14.

Under such circumstances many materials would be injured by the excessive compacting to which they would be subjected if the screw continued to operate, even if injury did not result to the apparatus. In the construction shown, whenever the material beneath the blades becomes compacted more than a predetermined amount, the rear edge of the blade is lifted thereby turning the associated crank 19 and raising shaft 23, lever 25 and weight 27. The degree of pressure which may be exerted upon the material by the blades is regulated by adjusting weight 27 A feature of the device to which particular attention is drawn is the fact that the blades are mounted about a substantially median axis and the switching of the blades into a plane normal to the axis of sleeve 18 is brought about by the greater resistance of the compacted-material under the lower edge of the blade as compared with the resistance of the less compacted material under the forward edge of the blade.

Yielding blades for propelling liquids have'been constructed to turn towards a plane normal to their axis of rotation as resistance of the liquid to the propelling force of the blade increased; but when such a blade is used to propel liquid, the resistance to the forward portion of the blade is as great as to the rear portion thereof. For this reason, a construction such as shown in the accompanying drawings would not be suitable to propel liquids as the pressure exerted upon the liquid would not turn the blades into a plane normal to their axis of rotation.

The purpose for which the material was compacted might be varied and the exact construction of the blades, their connections, and their driving means might be varied within the scope of the appended claims without departing from the invention.

What I claim is:

1. A propeller for use with granular or pulverulent material, said propeller comprising a sleeve, a blade mounted upon a stem extending radially through the sleeve, the inner end of the stem being turned at an angle to the plane of the blade so as to form a crank arm, a plunger in the sleeve in cooperative relation with said crank arm and means constantly tending to move the plunger in a direction to turn the blade at an angle to a plane normal to the axis of the sleeve, the blade being so constructed with relation to its stem that resistance of the material tends to force it into a plane normal to the axis of the sleeve against the resistance of the plunger.

2. A propeller comprising a vertical casing, a rotatable sleeve mounted in the easing, a radial stem extending through the sleeve and having a propeller blade on its outer end and a crank arm on its inner end, a plunger within the sleeve resting on said crank arm, and adjustable means constantly tending to drive the plunger downward, the crank arm being at such an angle to the blade that the plunger resting thereon tends to tilt the rear edge of the blade downward and the forward edge of the blade upward.

.3. A propeller comprising a vertical casing, a rotatable sleeve mounted in the casing, a radial stem extending through the sleeve and having a propeller blade on its outer end and a crank arm on its inner end, a plunger within the sleeve resting on said crank arm, and adjustable means constantly tending to drive the plunger downward, the crank arm being at such an angle to the blade that the plunger resting thereon tends to tilt the rear edge of the blade downward and the forward edge of the blade upward, the area of the blade on the two sides of the axis of said stem being substantially equal.

4. A propeller for propelling granular or powdery material comprising a propeller blade, means to drive the blade through material, a stem midway of said blade, and meansconstantly tending to move the rear edge of the blades towards the direction in ESLI A. MARSH. 

